The interior arrangement of wall columns, horizontal beams and cornice bracketing corresponds with that on the outside.
In the former the main supporting member or members may be an arch ring or arched ribs, suspension chains or ropes, or a pair of girders, beams or trusses.
Hence slabs or beams of long span should not be built of plain concrete, though when reinforced with steel it is admirably adapted for these purposes.
The structures in which steel concrete is used may be analysed as consisting essentially of (I) walls, (2) columns, (3) piles, (4) beams, (5) slabs, (6) arches.
Concrete by itself, though strong in compression, can offer but little resistance to tensile and shearing stresses, and as these stresses always occur in beams the problem arises how best to arrange the steel so as to assist the concrete in bearing them.